PREVIEW: SAS Who Dares Wins (S6E4), Channel 4

The remaining recruits are placed in pairs as they take on the threat of chemical warfare, with exposure to CS gas, and perform a fast-paced extraction in near-freezing water.

Those who cannot work properly as a pair will be removed from the selection immediately. For the final part of this phase, the pairs are separated and pitted against each other in brutal hand-to-hand combat.

SAS: Who Dares Wins continues Sunday at 9pm on Channel 4.